<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .box {
            width: 300px;
            height: 300px;
            background-color: pink;
            margin: 200px;
        }
    </style>
</head>

<body>
    <div class="box"></div>
    <script>
        //我们在盒子内点击,想要得到鼠标距离盒子左右的距离
        //首先得到鼠标在页面的坐标(e.pageX e.pageY)
        //其次得到盒子在页面中的距离(box.offsetLeft,box.offsetTop)
        //用鼠标距离页面的坐标减去盒子在页面中的距离,得到鼠标在盒子内的坐标
        var box = document.querySelector('.box');
        box.addEventListener('mousemove', function(e) {
            var x = e.pageX - this.offsetLeft;
            var y = e.pageY - this.offsetTop;
            this.innerHTML = '当前鼠标点击的x坐标是:' + x + ' y坐标是:' + y;
        })
    </script>
</body>

</html>